Computers, televisions, telephones and other electronic products contain large numbers of essential electronic semiconductor devices. To produce electronic products, hundreds or thousands of semiconductor devices are manufactured in a very small space, using lithography techniques on semiconductor substrates, such as on silicon wafers. Due to the extremely small dimensions involved in manufacturing semiconductor devices, contaminants on the semiconductor substrate material, such as particles of dust, dirt, paint, metal, etc. lead to defects in the end products.
To exclude contaminants, semiconductor substrates are processed within clean rooms. Clean rooms are enclosed areas or rooms within a semiconductor manufacturing facility, designed to keep out contaminants. All air provided to a clean room is typically highly filtered to prevent airborne contaminants from entering into or circulating within the clean room. Special materials and equipment are needed to maintain contaminants within the clean room at adequately low levels. Consequently, construction and maintenance of clean rooms can be time consuming and costly. As a result, the semiconductor processing equipment installed within a clean room should preferably be compact, so that large numbers of semiconductor wafers can be processed within a smaller space, thereby reducing space requirements and costs. Accordingly, there is a need for smaller semiconductor processing equipment, to reduce clean room space requirements.
Existing automated processing systems use robots to carry the wafers or workpieces. These robots are designed to avoid creating particles which could contaminate the semiconductors. However, even with careful design, material selection, and robot operation, particles may still be created by these robots, via their moving parts. Accordingly, there is a need for improved techniques for processing semiconductor substrate materials with very low levels of contamination to maintain 5 the level of defects at acceptable levels.
Many automated processing systems use centrifugal processors, which spin the wafers at high speed, while spraying or otherwise applying process fluids and/or gases onto the wafers. The rotors typically hold a batch of wafers in a parallel array. While the close spacing of the wafers in such rotors has advantages, such as providing a compact design, if a single wafer breaks while within the rotor, the wafer pieces will often damage adjacent wafers.
During centrifugal processing of wafers within a rotor, it is important to have the process liquids contact the wafer surfaces in a substantially uniform way. Uniform contact helps to provide all useable surfaces of the wafers with substantially consistent processing. As a result, all wafers within the batch of wafers in the rotor (as well as subsequent batches) are generally uniformly processed. It is advantageous for the rotor in the process chamber (as well as any tray or carrier installed into the rotor) to have a structure which allows the process liquids and/or gases to be sprayed through and onto the wafers. On the other hand, the wafers must be adequately supported to avoid excessive stress and wafer breakage so that the rotor must have adequate structural elements. In addition, as the rotor is typically cantilevered on a shaft extending from the back end of the centrifugal process chamber, and because the rotor may be exposed to large centrifugal forces when spinning at high speed, while remaining substantially centrifugally balanced, the rotor must be relatively rigid and strong. These requirements present design engineering challenges, as the increased material mass and thicker wall sections often used to achieve a strong and rigid design also tend to provide a more closed rotor structure, tending to limit the inflow/inspray of process fluids or gases.
Accordingly, there is a need for improved motor technology and methods for handling and processing wafers.